Heat oven to 325°F. Spray or lightly grease 2 large cookie sheets. In large bowl, beat butter and powdered sugar with electric mixer on medium speed until light and fluffy. Beat in vanilla and food color. On low speed, beat in flour just until mixed. Stir in chopped pecans.
Divide dough into 4 equal parts; shape each into ball. Place 2 balls of dough on each cookie sheet, on opposite ends. With rolling pin or floured fingers, gently flatten and shape each ball into 6-inch circle. With large knife, divide and cut each round into 8 wedges, slightly separating each cut with knife. Poke tops of wedges with fork, and place 1 pecan half in middle of each outer edge to make tree trunk.
Bake 15 to 18 minutes or until firm but not brown. While still warm, cut into wedges again. Cool completely on cookie sheets, about 30 minutes.
Place cooled tree wedges on cooling racks or waxed paper. Place baking chips in small resealable freezer plastic bag. Microwave on High 40 to 60 seconds, turning bag over after 30 seconds. Squeeze bag gently until chips are melted and smooth. Cut small tip off one corner of bag, and drizzle side to side over wedges to make tree garland. Sprinkle with sugar Top each tree with star.